Physical activity has is considered as one of the most important health related aspects of the 21st century. In Norway, large epidemiological studies show that only about 30% of the adult population meet the physical activity recommendations of 150 minutes per week with moderate-to-vigorous intensity physical activity. Also, studies show that there are large dropout rates from lifestyle interventions, and that approximately 50% drop out from physical activity interventions within 6 months after start. One explanation for the dropout is performance of exercise with too vigorous intensities.